U.S. patent number 8,619,916 [Application Number 12/987,646] was granted by the patent office on 2013-12-31 for apparatus for receiving signal and method of compensating phase mismatch thereof.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. The grantee listed for this patent is Ilyong Jong. Invention is credited to Ilyong Jong.
United States Patent |
8,619,916 |
Jong |
December 31, 2013 |
Apparatus for receiving signal and method of compensating phase
mismatch thereof
Abstract
An apparatus for receiving a signal includes a training signal
generator generating a training signal for each frequency channel;
an in-phase and quadrature-phase (IQ) signal generator generating a
first in-phase signal and a first quadrature-phase signal using the
training signal in a first operation mode and generating a second
in-phase signal and a second quadrature-phase signal using a
receiving signal in a second operation mode; an IQ mismatch
compensator which makes the first in-phase signal and first
quadrature-phase signal generated in response to each frequency
channel converge for a reference time in the first operation mode
to obtain a phase mismatch compensation coefficient for selected
frequency channels and after generating a look-up table using the
phase mismatch compensation coefficient, compensates the second
in-phase signal and the second quadrature-phase signal using the
phase mismatch compensation coefficient in the second operation
mode; and a memory in which the look-up table is stored.
Inventors: |
Jong; Ilyong (Seongnam-si,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Jong; Ilyong |
Seongnam-si |
N/A |
KR |
|
|
Assignee: |
Samsung Electronics Co., Ltd.
(Gyeonggi-do, KR)
|
Family
ID: |
44559960 |
Appl.
No.: |
12/987,646 |
Filed: |
January 10, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110222631 A1 |
Sep 15, 2011 |
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Foreign Application Priority Data
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Mar 11, 2010 [KR] |
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10 2010 0021904 |
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Current U.S.
Class: |
375/322 |
Current CPC
Class: |
H04L
27/3863 (20130101) |
Current International
Class: |
H03K
9/06 (20060101) |
Field of
Search: |
;375/322 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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06-268703 |
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Sep 1994 |
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JP |
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2003-087344 |
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Mar 2003 |
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JP |
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2007-0049665 |
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May 2007 |
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KR |
|
Primary Examiner: Torres; Juan A
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Claims
What is claimed is:
1. An apparatus for receiving a signal, comprising: a memory; a
training signal generator configured to generate a training signal
corresponding to each of one or more frequency channels; an
in-phase and quadrature-phase (IQ) signal generator configured to
generate a first in-phase signal and a first quadrature-phase
signal using the training signal in a first operation mode and
generate a second in-phase signal and a second quadrature-phase
signal using a received signal in a second operation mode; and an
IQ mismatch compensator configured to cause the first in-phase
signal and the first quadrature-phase signal generated in response
to each of the one or more frequency channels to converge for a
reference time in the first operation mode to obtain a phase
mismatch compensation coefficient, configured to obtain the phase
mismatch compensation coefficient with respect to selected
frequency channels from among the one or more frequency channels
and store the phase mismatch compensation coefficient in a look-up
table in the memory, and configured to compensate the second
in-phase signal and the second quadrature-phase signal using the
phase mismatch compensation coefficient included in the look-up
table in the second operation mode, after obtaining the phase
mismatch compensation coefficient, wherein the IQ mismatch
compensator includes, a feedback signal combiner configured to
combine an inputted in-phase signal with a feedback in-phase signal
and a feedback quadrature-phase signal outputted from an in-phase
and quadrature-phase mismatch compensator to generate a combined
in-phase signal, and configured to combine an inputted
quadrature-phase signal with the feedback in-phase signal and the
feedback quadrature-phase signal outputted from an in-phase and
quadrature-phase mismatch compensator to generate a combined
quadrature-phase signal, a signal determiner configured to generate
a determined in-phase signal and a determined quadrature-phase
signal by determining an absolute value of the combined in-phase
signal and the combined quadrature-phase signal respectively, and a
mismatch compensator configured to converge the determined in-phase
signal and the determined quadrature-phase signal for a reference
time in the first operation mode to extract the phase mismatch
compensation coefficient, and configured to apply the phase
mismatch compensation coefficient to the determined in-phase signal
and the determined quadrature-phase signal in the second operation
mode to compensate a phase mismatch.
2. The apparatus for receiving a signal of claim 1, wherein the
feedback signal combiner comprises: a first multiplier configured
to multiply an inputted in-phase signal by a feedback in-phase
signal; an inverter configured to apply a minus sign to the
inputted quadrature-phase signal; a second multiplier multiplying
an output of the inverter by the feedback quadrature-phase signal;
a first adder configured to subtract an output of the second
multiplier from an output of the first multiplier; a second adder
configured to generate a combined in-phase signal by subtracting an
output of the first adder from the inputted in-phase signal; a
third multiplier configured to multiply an output of the inverter
by the feedback in-phase signal; a fourth multiplier configured to
multiply the inputted in-phase signal by a feedback
quadrature-phase signal; a third adder configured to add outputs of
the third and fourth multipliers; and a fourth adder configured to
generate a combined quadrature-phase signal by subtracting an
output of the third adder from the inputted quadrature-phase
signal.
3. The apparatus for receiving a signal of claim 1, wherein the
signal determiner comprises: a first absolute value operator
configured to determine an absolute value of the combined in-phase
signal; a second absolute value operator configured to determine an
absolute value of the combined quadrature-phase signal; a fifth
adder configured to generate a determined in-phase signal by
subtracting an output of the second absolute value operator from an
output of the first absolute value operator; a first sign bit
extractor configured to extract a sign bit from the combined
in-phase signal; a second sign bit extractor configured to extract
a sign bit from the combined quadrature-phase signal; an exclusive
OR operator configured to perform an exclusive-OR operation on an
output of the first sign bit extractor and an output of the second
sign bit extractor; a minimum value determiner configured to
determine a minimum value of the output of the first absolute value
operator and the output of the second absolute value operator; and
a sign setting part configured to generate a determined
quadrature-phase signal by setting a sign to an output of the
minimum value determiner by an output of the exclusive OR
operator.
4. The apparatus for receiving a signal of claim 1, wherein the
mismatch compensator comprises: a first delay device configured to
delay the determined in-phase signal for a reference time; a sixth
adder which is located at a front part of the first delay device
configured to combine the determined in-phase signal with an output
of the first delay device; a first switch configured to switch the
output of the first delay device to an input of the sixth adder in
a first operation mode and to switch so that the phase mismatch
compensation coefficient is applied to the output of the first
delay device in a second operation mode; a second delay device
configured to delay the determined quadrature-phase signal for a
reference time; a seventh adder which is located at a front part
the second delay device and configured to combine the determined
quadrature-phase signal with an output of the second delay device;
a second switch configured to switch the output of the second delay
device to an input of the seventh adder in a first operation mode
and switch so that the phase mismatch compensation coefficient is
applied to the output of the second delay device in a second
operation mode; and a compensation signal output device configured
to extract a phase mismatch compensation coefficient converged for
a reference time by controlling the first and second switches in a
first operation mode and outputting an in-phase signal of which a
phase mismatch is compensated and a quadrature-phase signal of
which a phase mismatch is compensated by controlling the first and
second switches in a second operation mode.
5. The apparatus for receiving a signal of claim 1, wherein the IQ
mismatch compensator, in a second operation mode, is configured to
determine a frequency channel of a receiving signal, interpolate
phase mismatch compensation coefficients of at least two frequency
channels adjacent to the determined frequency channel to determine
a phase mismatch compensation coefficient of the determined
frequency channel and output the determined phase mismatch
compensation coefficient to a mismatch compensator.
6. The apparatus for receiving a signal of claim 1, wherein the
memory is configured to store a phase mismatch compensation
coefficient used in the receiver according to one of an initial
operation and an awake operation of the receiver.
7. A method of compensating a phase mismatch, comprising:
generating a training signal corresponding to each of one or more
frequency channels in a first operation mode and converging a first
in-phase signal and a first quadrature-phase signal generated using
the training signal for a reference time to obtain a phase mismatch
compensation coefficient; obtaining the phase mismatch compensation
coefficient from channels selected in the first operation mode and
generating a look-up table using the obtained phase mismatch
compensation coefficients; and compensating a phase mismatch of a
second in-phase signal and a second quadrature-phase signal
generated using a receiving signal in a second operation mode using
the phase mismatch compensation coefficient extracted from the
look-up table, wherein obtaining the phase mismatch compensation
coefficient includes, combining the first in-phase signal and the
first quadrature-phase signal with a feedback signal; generating a
combined in-phase signal and a combined quadrature-phase signal by
combining the combined first in-phase signal and the combined first
quadrature-phase signal with a feedback in-phase signal and a
feedback quadrature-phase signal; generating an absolute in-phase
signal and an absolute quadrature-phase signal by determining an
absolute value of the combined in-phase signal and the combined
quadrature-phase signal, respectively; generating a determined
in-phase signal by subtracting the absolute quadrature-phase signal
from the absolute in-phase signal; determining a sign by extracting
a sign from each of the combined in-phase signal and the combined
quadrature-phase signal to perform an exclusive-OR operation on the
extracted sign; determining a minimum value of the absolute value
in-phase signal and the absolute value quadrature phase signal;
setting the sign to the minimum value to generate a determined
quadrature-phase signal; and combining the determined in-phase
signal and the combined quadrature-phase signal with a delayed
in-phase signal and a delayed quadrature-phase signal and
determining a phase mismatch compensation coefficient by converging
for a reference time.
8. The method of claim 7, wherein compensating the phase mismatch
comprises detecting phase mismatch compensation coefficients of at
least two frequency channels adjacent to a frequency channel of the
receiving signal interpolated from the look-up table and
interpolating the detected phase mismatch compensation coefficients
to determine a phase mismatch compensation coefficient.
9. An apparatus for receiving a signal, comprising: a memory; a
training signal generator configured to generate a training signal
corresponding to each of one or more frequency channels; an
in-phase and quadrature phase (IQ) signal generator configured to
operate in a first operation mode and a second operation mode such
that in the first operation mode, the IQ signal generator is
configured to generate a first in-phase signal and a first
quadrature-phase signal based on the training signal, and in the
second operation mode, the IQ signal generator is configured to
generate a second in-phase signal and a second quadrature-phase
signal based on a receiving signal; and an IQ mismatch compensator
configured to operate in the first operation mode and the second
operation mode such that, in the first operation mode, the IQ
mismatch compensator is configured to obtain a phase mismatch
compensation coefficient based on selected frequency channels from
among the one or more frequency channels by causing the first
in-phase signal and the first quadrature-phase signal to converge
for a reference time, and configured to store the obtained phase
mismatch compensation coefficient in a look-up table in the memory,
and in the second operation mode, the IQ mismatch compensator is
configured to compensate the second in-phase signal and the second
quadrature-phase signal using the phase mismatch compensation
coefficient included in the look-up table, wherein the IQ mismatch
compensator includes, a feedback signal combiner configured to
combine an inputted in-phase signal with a feedback in-phase signal
and a feedback quadrature-phase signal outputted from an in-phase
and quadrature-phase mismatch compensator to generate a combined
in-phase signal, and configured to combine an inputted
quadrature-phase signal with the feedback in-phase signal and the
feedback quadrature-phase signal outputted from an in-phase and
quadrature-phase mismatch compensator to generate a combined
quadrature-phase signal, a signal determiner configured to generate
a determined in-phase signal and a determined quadrature-phase
signal by determining an absolute value of the combined in-phase
signal and the combined quadrature-phase signal respectively, and a
mismatch compensator configured to converge the determined in-phase
signal and the determined quadrature-phase signal for a reference
time in the first operation mode to extract the phase mismatch
compensation coefficient, and configured to apply the phase
mismatch compensation coefficient to the determined in-phase signal
and the determined quadrature-phase signal in the second operation
mode to compensate a phase mismatch.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This U.S. non-provisional patent application claims priority under
35 U.S.C. .sctn.119 to Korean Patent Application No.
10-2010-0021904, filed on Mar. 11, 2010, in the Korean Intellectual
Property Office (KIPO), the entire contents of which are hereby
incorporated by reference.
BACKGROUND
1. Field
Example embodiments herein relates to an apparatus for receiving a
signal, and more particularly, to an apparatus for receiving a
signal preventing deterioration of receiving performance due to a
mismatch between an in-phase I signal and a quadrature-phase Q
signal and a method of compensating a phase mismatch thereof.
2. Related Art
Generally, an apparatus for receiving a signal in a communication
system, that is, a receiver includes a low noise amplifier (LNA).
The low noise amplifier (LNA) amplifies a signal of a received
signal mixed with a noise on a wireless channel while suppressing
the noise. The receiver processes an output signal of the low noise
amplifier by wireless.
In the case that an output signal of the low noise amplifier (LNA)
is processed by wireless, the receiver down-converts a received
signal to generate an in-phase (hereinafter it is referred to as I)
signal and a quadrature-phase (hereinafter it is referred to as Q).
A phase difference of 90.degree. exists between the I signal and
the Q signal.
The receiver includes a local oscillator (LO) and a mixer to
generate an I signal and a Q signal. The local oscillator (LO)
generates a local oscillating signal and the local oscillating
signal is outputted to a first mixer generating an I signal and to
a second mixer generating a Q signal. Each of the first mixer and
the second mixer mixes an output signal of the low noise amplifier
and a local oscillating signal to generate an I signal and a Q
signal respectively. The I and Q signals outputted from each of the
first mixer and the second mixer pass through a band pass filter to
be band pass-filtered. After that, the band pass-filtered signals
pass through an analog to digital converter (ADC) to be converted
into digital signals and received in the receiver.
The I signal and the Q signal outputted from each of the mixers
should have a phase difference of 90.degree.. In the case that the
I signal and the Q signal do not have a phase difference of
90.degree. due to performance of the mixers, a mismatch occurs
between the I signal and the Q signal. A mismatch between the I
signal and the Q signal distorts a base band signal received to
deteriorate receiving performance of the receiver.
SUMMARY
Example embodiments provide an apparatus for receiving a signal.
The apparatus for receiving a signal may include a memory, a
training signal generator generating a training signal
corresponding to each frequency channel; an IQ signal generator
generating a first in-phase signal and a first quadrature-phase
signal using the training signal in a first operation mode and
generating a second in-phase signal and a second quadrature-phase
signal using a received signal in a second operation mode; and an
IQ mismatch compensator which makes the first in-phase signal and
the first quadrature-phase signal generated in response to each
frequency channel converge for a reference time in the first
operation mode to obtain a phase mismatch compensation coefficient
and after obtaining a phase mismatch compensation coefficient with
respect to selected frequency channels and store the phase mismatch
compensation coefficient in a look-up table in the memory,
compensates the second in-phase signal and the second
quadrature-phase signal using the phase mismatch compensation
coefficient included in the look-up table in the second operation
mode.
Example embodiments also provide a method of compensating a phase
mismatch of an apparatus for receiving a signal. The method may
include generating a training signal corresponding to each
frequency channel in a first operation mode and converging a first
in-phase signal and a first quadrature-phase signal generated using
the training signal for a specific or reference time to obtain a
phase mismatch compensation coefficient; obtaining a phase mismatch
compensation coefficient from channels selected in the first
operation mode and generating a look-up table using the obtained
phase mismatch compensation coefficients; and compensating a phase
mismatch of a second in-phase signal and a second quadrature-phase
signal generated using a receiving signal in a second operation
mode using the phase mismatch compensation coefficient extracted
from the look-up table.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and advantages of example embodiments
will become more apparent by describing in detail example
embodiments with reference to the attached drawings. The
accompanying drawings are intended to depict example embodiments
and should not be interpreted to limit the intended scope, of the
claims. The accompanying drawings are not to be considered as drawn
to scale unless explicitly noted.
FIG. 1 is a drawing illustrating a structure of a receiver in
accordance with an example embodiment.
FIG. 2 is a drawing illustrating a structure of an IQ mismatch
compensator of FIG. 1 by example.
FIG. 3 is a drawing illustrating a feedback signal combiner of FIG.
2 by example.
FIG. 4 is a drawing illustrating a structure of a signal determiner
of FIG. 2 by example.
FIG. 5 is a drawing illustrating a structure of a mismatch
compensator of FIG. 2 by example.
FIG. 6 is a flow chart illustrating an operation of a receiver in a
first operation mode in accordance with an example embodiment.
FIG. 7 is a flow chart illustrating an operation of a receiver in a
second operation mode in accordance with an example embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Detailed example embodiments are disclosed herein. However,
specific structural and functional details disclosed herein are
merely representative for purposes of describing example
embodiments. Example embodiments may, however, be embodied in many
alternate forms and should not be construed as limited to only the
embodiments set forth herein.
Accordingly, while example embodiments are capable of various
modifications and alternative forms, embodiments thereof are shown
by way of example in the drawings and will herein be described in
detail. It should be understood, however, that there is no intent
to limit example embodiments to the particular forms disclosed, but
to the contrary, example embodiments are to cover all
modifications, equivalents, and alternatives falling within the
scope of example embodiments. Like numbers refer to like elements
throughout the description of the figures.
It will be understood that, although the terms first, second, etc.
may be used herein to describe various elements, these elements
should not be limited by these terms. These terms are only used to
distinguish one element from another. For example, a first element
could be termed a second element, and, similarly, a second element
could be termed a first element, without departing from the scope
of example embodiments. As used herein, the term "and/or" includes
any and all combinations of one or more of the associated listed
items.
It will be understood that when an element is referred to as being
"connected" or "coupled" to another element, it may be directly
connected or coupled to the other element or intervening elements
may be present. In contrast, when an element is referred to as
being "directly connected" or "directly coupled" to another
element, there are no intervening elements present. Other words
used to describe the relationship between elements should be
interpreted in a like fashion (e.g., "between" versus "directly
between", "adjacent" versus "directly adjacent", etc.).
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
example embodiments. As used herein, the singular forms "a", "an"
and "the" are intended to include the plural forms as well, unless
the context clearly indicates otherwise. It will be further
understood that the terms "comprises", "comprising,", "includes"
and/or "including", when used herein, specify the presence of
stated features, integers, steps, operations, elements, and/or
components, but do not preclude the presence or addition of one or
more other features, integers, steps, operations, elements,
components, and/or groups thereof.
It should also be noted that in some alternative implementations,
the functions/acts noted may occur out of the order noted in the
figures. For example, two figures shown in succession may in fact
be executed substantially concurrently or may sometimes be executed
in the reverse order, depending upon the functionality/acts
involved.
Example embodiments herein relate to an apparatus for receiving a
signal, and more particularly, to an apparatus for receiving a
signal preventing deterioration of receiving performance due to a
mismatch between an in-phase I signal and a quadrature-phase Q
signal and a method of compensating a phase mismatch thereof.
An apparatus for receiving a signal, that is, a receiver has two
operation modes. A first operation mode is a calibration mode which
generates a phase mismatch compensation coefficient for phase
mismatch compensation and a second operation mode is a normal mode
which compensates a phase mismatch of I signal and Q signal of a
received signal by applying a phase mismatch compensation
coefficient to a received signal.
FIG. 1 is a drawing illustrating a structure of a receiver in
accordance with an example embodiment.
Referring to FIG. 1, a receiver includes a low noise amplifier
(LNA) 111, a local oscillator (LO) 113, a first mixer 115, a second
mixer 117, a first low pass filter 119, a second low pass filter
121, a first analog to digital converter (ADC) 123, a second analog
to digital converter (ADC) 125, an in-phase-quadrature-phase
mismatch compensator 127, a digital signal processor 129, a memory
131 and a training signal generator 133.
First, a case that a receiver operates by a first operation mode is
described.
The training signal generator 133 divides the whole frequency band
which a receiver can receive into the predetermined number of
frequency channels. The training signal generator 133 generates a
training signal having the same frequency as selected frequency
channels among the whole frequency channel.
The local oscillator 113 generates local oscillating signals to
generate an I signal and a Q signal.
The first mixer 115 receives a training signal and mixes the
training signal with the local oscillating signal to generate an I
signal.
The second mixer 117 receives a training signal and mixes the
training signal with the local oscillating signal to generate a Q
signal. The second mixer 117 generates a Q signal having a phase
difference of 90.degree. with respect to an I signal of the first
mixer 115.
The first low pass filter 119 low pass-filters an I signal
outputted from the first mixer 115. The second low pass filter 121
low pass-filters a Q signal outputted from the second mixer
117.
The first analog to digital converter 123 converts the low
pass-filtered I signal into a digital signal and the second analog
to digital converter 125 converts the low pass-filtered Q signal
into a digital signal.
Here, the local oscillator 113, the first mixer 115 and the second
mixer 117 may constitute an in-phase-quadrature-phase signal
generator (hereinafter it is referred to as `IQ signal generator`)
generating an IQ signal and the IQ signal generator may further
include the first low pass filter 119, the second low pass filter
121, the first analog to digital converter 123 and the second
analog to digital converter 125.
The IQ mismatch compensator 127 makes the generated I signal and Q
signal converge for a or reference time using a training signal to
obtain a phase mismatch compensation coefficient. The IQ mismatch
compensator 127 obtains a phase mismatch compensation coefficient
with respect to the one or more frequency channels selected to
generate a training signal and if a phase mismatch compensation
coefficient with respect to the whole frequency channel is
obtained, the IQ mismatch compensator 127 generates a look-up table
corresponding to each frequency channel to store on the memory
131.
The memory 131 stores the look-up table. The memory 131 can store a
phase mismatch compensation coefficient used in the receiver before
according to one of an initial operation and an awake operation of
the receiver.
After the receiver completes a look-up table generation with
respect to the whole frequency in the first operation mode, the
receiver operates in the second operation mode. Next, a case that
the receiver operates by the second operation mode is
described.
The low noise amplifier (LNA) receives signals through an antenna
and amplifies the received signals mixed with a noise on a wireless
channel while suppressing the noise.
The local oscillator 113 generates local oscillating signals to
generate an I signal and a Q signal.
The first mixer 115 receives a receiving signal and mixes the
receiving signal with the local oscillating signal to generate an I
signal.
The second mixer 117 receives a receiving signal and mixes the
receiving signal with the local oscillating signal to generate a Q
signal. The second mixer 117 generates a signal having a phase
difference of 90.degree. with respect to the first mixer 115.
The first low pass filter 119 low pass-filters an I signal
outputted from the first mixer 115. The second low pass filter 121
low pass-filters a Q signal outputted from the second mixer
117.
The first analog to digital converter 123 converts the low
pass-filtered I signal into a digital signal and the second analog
to digital converter 125 converts the low pass-filtered Q signal
into a digital signal.
Here, the local oscillator 113, the first mixer 115 and the second
mixer 117 may constitute the IQ signal generator generating an IQ
signal and the IQ signal generator may further include the first
low pass filter 119, the second low pass filter 121, the first
analog to digital converter 123 and the second analog to digital
converter 125.
The IQ mismatch compensator 127 determines a frequency channel of
the receiving signal and compensates the generated I and Q signals
with a phase mismatch compensation coefficient using the receiving
signal. The IQ mismatch compensator 127 extracts a phase mismatch
compensation coefficient corresponding to a frequency channel from
the look-up table stored in the memory 131 and can compensate a
phase mismatch of I and Q signals using the extracted phase
mismatch compensation coefficient.
The digital signal processor 129 digital signal-processes I and Q
signals of which a phase mismatch is compensated to receive a
signal.
FIG. 2 is a drawing illustrating a structure of an IQ mismatch
compensator of FIG. 1 by example.
Referring to FIG. 2, the IQ mismatch compensator 127 includes a
feedback signal combiner 211, a signal determiner 213, a mismatch
compensator 215 and a mismatch compensation coefficient management
device 217.
The feedback signal combiner 211 receives a feedback I signal and a
feedback Q signal outputted before through the mismatch compensator
215. An I signal and a Q signal inputted into the feedback signal
combiner 211 are combined with a feedback I signal and a feedback Q
signal respectively to generate a combined I signal and a combined
Q signal respectively.
The signal determiner 213 performs an absolute value operation on
the combined I signal and the combined Q signal to generate an
absolute value I signal and an absolute value Q signal. The signal
determiner 213 generates an I signal determined by subtracting an
absolute value quadrature-phase signal from an absolute I signal.
The signal determiner 213 extracts a sign bit from the combined I
signal and the combined Q signal respectively, determines a sign by
performing an exclusive OR-operation on the extracted sign bits and
sets a sign to a signal having a minimum value of the absolute
value I signal and the absolute Q signal to generate a determined Q
signal.
The feedback signal combiner 211 and the signal determiner 213
perform the same operation on an I signal and a Q signal
respectively inputted from the first operation mode and the second
operation mode.
The mismatch compensator 215 makes an I signal and a Q signal
determined in the first operation mode converge for a or reference
time to extract a phase mismatch compensation coefficient. The
mismatch compensator 215 can generate a look-up table in which a
phase mismatch compensation coefficient is mapped by a frequency
channel using a phase mismatch compensation coefficient.
As an illustration, a look-up table is illustrated in a table 1
below.
TABLE-US-00001 TABLE 1 Frequency channel index Phase mismatch
compensation coefficient C.sub.0 1 C.sub.1 . . . . . . 0 C.sub.si-1
S.sub.i C.sub.si . . . . . . M C.sub.si
The look-up table includes phase mismatch compensation coefficients
Ci. Each frequency channel index means an index representing each
frequency channel.
The mismatch compensation coefficient management device 217 selects
a frequency channel corresponding to a receiving signal in the
second operation mode and can provide a phase mismatch compensation
coefficient corresponding to the selected frequency channel to the
mismatch compensator 215.
The mismatch compensation coefficient management device 217 may
select one frequency channel most adjacent to a frequency channel
corresponding to a receiving signal to extract a phase mismatch
compensation coefficient and may also interpolate phase mismatch
compensation coefficients of at least two frequency channels
adjacent to a frequency channel corresponding to a receiving signal
to determine a phase mismatch compensation coefficient.
In the case that the mismatch compensation coefficient management
device 217 selects one frequency channel corresponding to a
receiving signal, Cn inputted in the mismatch compensator 215 may
become Ci and in the case of using an interpolation to compensate a
phase mismatch with respect to two adjacent channels, it may be
represented by a mathematical formula I below.
.times..times..times..times..times. ##EQU00001##
In the mathematical formula I, as an example, an interpolation is
performed on two adjacent channels to obtain Cn value. Here, n has
values of 0.about.M-1.
The mismatch compensator 215 applies a phase mismatch compensation
coefficient to a determined I signal and a determined Q signal to
compensate a phase mismatch.
FIG. 3 is a drawing illustrating a feedback signal combiner of FIG.
2 by example.
Referring to FIG. 3, the feedback signal combiner 211 includes a
first multiplier 311, a first adder 313, a second adder 315, a
fourth adder 317, an inverter 319, a second multiplier 321, a third
multiplier 325, a fourth multiplier 323 and a third adder 327.
The first multiplier 311 multiplies an inputted I signal by a
feedback I signal. The inverter 319 applies a minus sign to an
inputted I signal.
The second multiplier 321 multiplies an output of the inverter 319
by a feedback Q signal.
The first adder 313 adds an output of the first multiplier 311 to
an output of the second multiplier 321 to which a minus sign is
applied. That is, the first adder 313 subtracts an output of the
second multiplier 321 from an output of the first multiplier
311.
The second adder 315 adds an inputted I signal to an output of the
first adder 313 to which a minus sign is applied. That is, the
second adder 315 subtracts an output of the first adder 313 from an
inputted I signal to generate a combined I signal (I' signal).
The third multiplier 325 multiplies an output of the inverter 319
by a feedback I signal.
The fourth multiplier 323 multiplies an inputted I signal by a
feedback Q signal.
The third adder 327 adds an output of the third multiplier 325 and
an output of the fourth multiplier 323.
The fourth adder 317 adds an inputted Q signal to an output of the
third adder 327 to which a minus sign is applied. That is, the
fourth adder 317 subtracts an output of the third adder 327 from an
inputted Q signal to generate a combined Q signal (Q' signal).
FIG. 4 is a drawing illustrating a structure of a signal determiner
of FIG. 2 by example.
Referring to FIG. 4, the signal determiner 213 includes a first
absolute value operator 411, a second absolute value operator 413,
a fifth adder 415, a minimum value determiner 417, a first sign bit
extractor 419, a second sign bit extractor 421, an exclusive OR
operator 423 and a sign setting part 425.
The first absolute value operator 411 operates on a combined I
signal to generate an absolute value I signal. The second absolute
value operator 413 operates on a combined Q signal to generate an
absolute value Q signal.
The fifth adder 415 adds an absolute value I signal to an absolute
value Q signal to which a minus sign is applied. That is, the fifth
adder 415 subtracts an absolute value Q signal from an absolute
value I signal to generate a determined I signal (I'' signal).
The first sign bit extractor 419 extracts a sign bit from a
combined I signal. The second sign bit extractor 421 extracts a
sign bit from a combined Q signal.
The exclusive OR operator 423 performs an exclusive-OR operation on
sign bits extracted from the first sign bit extractor 419 and the
second sign bit extractor 421 to determine a sign.
The minimum value determiner 417 selects a minimum value of an
absolute value I signal and an absolute value Q signal.
The sign setting part 425 sets a sign determined by the exclusive
OR operator 423 to one signal of an absolute value I signal and an
absolute value Q signal having a minimum value selected by the
minimum value determiner 417 to generate a determined Q signal (Q''
signal).
FIG. 5 is a drawing illustrating a structure of a mismatch
compensator of FIG. 2 by example.
Referring to FIG. 5, the mismatch compensator 215 includes a sixth
adder 511, a seventh adder 513, a first delay device 515, a second
delay device 517, a first switch 519, a second switch 521 and a
convergence value output device 523.
The first delay device 515 delays a determined I signal.
The sixth adder 511 is located at a front part of the first delay
device 515 and adds a delay I signal switched from the first switch
519 to a determined I signal.
The first switch 519, in a first operation mode, switches an output
of the first delay device 515 to an input of the sixth adder 511.
The first switch 519, in a second operation mode, switches so that
a phase mismatch compensation coefficient Cn is applied to an
output of the first delay device 515.
The second delay device 517 delays a determined Q signal.
The seventh adder 513 is located at a front part of the second
delay device 517 and adds a delay Q signal switched from the second
switch 521 to a determined Q signal.
The second switch 521, in a first operation mode, switches an
output of the second delay device 517 to an input of the seventh
adder 513. The second switch 521, in a second operation mode,
switches so that a phase mismatch compensation coefficient Cn is
applied to an output of the second delay device 517.
The convergence value output device 523, in the first operation
mode, controls the first and second switches 519 and 521 to
feedback outputs of the delay devices 515 and 517 and converges for
a or reference time to extract a phase mismatch compensation
coefficient Ci. Also, the convergence value output device 523, in
the second operation mode, controls the first and second switches
519 and 521 to compensate a phase mismatch by applying a phase
mismatch compensation coefficient to a determined I signal and a
determined Q signal.
The convergence value output device 523 outputs a phase mismatch
compensation signal in the first operation mode and outputs signals
in which a mismatch between the I signal and the Q signal is
compensated, that is, a compensated I signal (I''' signal) and a
compensated Q signal (Q''' signal) in the second operation
mode.
FIG. 6 is a flow chart illustrating an operation of a receiver in a
first operation mode in accordance with an example embodiment.
Referring to FIG. 6, in a step of 611, the receiver selects N
number of frequency channels in the whole frequency band.
In a step of 613, the receiver sets i to an initial value.
In a step of 615, the receiver generates a training signal
corresponding to the selected frequency channel.
In a step of 617, the receiver generates an I signal and a Q signal
using the training signal.
In a step of 619, the receiver determines a mismatch compensation
coefficient converged for an IQ mismatch compensation with respect
to the selected frequency channel.
In a step of 621, the receiver checks whether i has the same value
as N-1 or not. Here, N is the number of carrier frequencies.
After checking, in the case that i does not have the same value as
N-1, a process goes to a step of 623.
In a step of 623, the receiver increases i by 1.
In the case that i has the same value as N-1, a process goes to a
step of 625.
In a step of 625, the receiver generates and stores a look-up table
for mismatch compensation, and then the flow came to an end. Phase
mismatch compensation coefficients are mapped and stored in the
look-up table by a frequency channel.
FIG. 7 is a flow chart illustrating an operation of a receiver in a
second operation mode in accordance with an example embodiment.
Referring to FIG. 7, in a step of 711, it is checked whether or not
the receiver receives a signal.
In the case that the receiver does not receive a signal, a process
goes to a step of 711.
In the case that the receiver receives a signal, a process goes to
a step of 713.
In the step of 713, the receiver selects a frequency channel of a
receiving signal.
In the step of 715, the receiver selects at least two frequency
channels adjacent to a determined frequency channel.
In a step of 717, the receiver interpolates the values of selected
frequency channels to obtain a phase mismatch compensation
coefficient. The receiver can interpolate a phase mismatch
compensation coefficient of each frequency channel using an
equation of various degrees (for example, a linear equation, a
quadratic equation, a cubic equation and so on). Here, the phase
mismatch compensation coefficient can be detected from a look-up
table set in the first operation mode.
The receiver may select one frequency channel most adjacent to a
determined frequency channel to obtain a phase, mismatch
compensation coefficient corresponding to the selected frequency
channel without performing the steps of 715 and 717.
In a step of 719, the receiver compensates a phase mismatch of a
receiving signal using an interpolated mismatch compensation
coefficient.
According to example embodiments, an apparatus for receiving a
signal generates a phase mismatch compensation coefficient for a
phase mismatch compensation using a training signal. It is possible
to compensate a phase difference between an in-phase signal and a
quadrature-phase signal generated from a mixer by reflecting the
phase mismatch compensation coefficient in a receiving signal to
compensate a phase mismatch. Also, performance of an apparatus for
receiving a signal can be improved by receiving a signal in which a
phase difference between an in-phase signal and a quadrature-phase
signal is compensated.
The above-disclosed subject matter is to be considered
illustrative, and not restrictive, and the appended claims are
intended to cover all such modifications, enhancements, and other
embodiments, which fall within the true spirit and scope of example
embodiments. Thus, to the maximum extent allowed by law, the scope
of example embodiments is to be determined by the broadest
permissible interpretation of the following claims and their
equivalents, and shall not be restricted or limited by the
foregoing detailed description.
Example embodiments having thus been described, it will be obvious
that the same may be varied in many ways. Such variations are not
to be regarded as a departure from the intended spirit and scope of
example embodiments, and all such modifications as would be obvious
to one skilled in the art are intended to be included within the
scope of the following claims.
* * * * *